Recovering IOS on a 2500 Series

The Cisco 2500 Series routers are a very common lab router however due to their age you may be required to recover the device from a corrupt IOS image. This lab will discuss and demonstrate the IOS recovery procedure for the 2500 Series Routers.

Real World Application

While the Cisco 2500 Series has long past lived its life in the grand scheme of networking, they are however commonly used in LAB environments. However, there are a lucky few that still run in production today with up times of 8+ years. Many engineers can plea that upgrading would be more beneficial to the network but the business see’s it as $$$. Why upgrade a device that works perfectly fine and has been for 8+ years? This procedure is commonly used on 2500 series routers that have a corrupt IOS image or NO image at all. It is common to purchase used routers with the flash memory erased; in which case you would be required to perform an image restoration process.

Lab Prerequisites

You’ll need a Cisco 2500 Series router that has a corrupt image or NO IOS image at all. If you wish to simulate this lab you can erase the flash on your device and reboot. Please note that you’ll need to backup the Cisco IOS image prior to erasing it unless you have another image on hand that you wish to load onto the device.

A console connection to the device is REQUIRED.

You’ll need a TFTP server installed on your PC to restore the image.

Lab Objectives

Boot the Cisco router into ROM mode by breaking the boot sequence using the keystroke CTRL+Pause Break

Change the configuration register to boot the ROM(BOOT) image. Configuration register to be used is 0x2141

Initialize the router by issuing the i command

Assign an IP address to the ethernet interface and configure a default gateway (if required)

Copy the Cisco IOS image from the TFTP server into flash memory.

Change the configuration register back to its default value and reload the device to ensure that the device boots up properly with the restored IOS image.

Lab Instruction

Step 1. Boot the router into ROM mode by breaking the boot sequence using the keystroke CTRL+PAUSE BREAK